Rangers are unlikely to seek sympathy in this, their defining off-field hour. Which is just as well; supporters of the Ibrox club's SPL rivals are positively purring about a potentially fatal wound being inflicted on Rangers in the not-so distant future.

Until the result of a much-publicised and discussed tax tribunal between Rangers and Her Majesty's Revenue and Customs is announced, uncertainty prevails. That seems to have reached first-team level, if the comments of Ally McCoist after last weekend's Scottish Cup defeat by Dundee United are anything to go by. For the defending league champions, the worst-case scenario is at least as plain as it has been for months; defeat in the tax case would prompt a bill in excess of £40m landing on the Ibrox doorstep. The Rangers route from there is ominously obvious – administration or even liquidation. But perhaps more fascinating is what that would entail for the SPL and for Rangers' fellow top-flight clubs.

Unsurprisingly, the wildest elements of glee surrounding Rangers' off-field predicament are emanating from fans of Celtic. The obsession each group of Old Firm supporters has with their biggest rivals is utterly tiresome but it is unlikely to disappear; Celtic's following will argue they are perfectly entitled to wallow in the possibility of upcoming misery for Rangers. If the roles were reversed, the same attitudes would prevail.

Elsewhere, supporters of other Scottish clubs with long memories will readily recall the lavishness – regarded as arrogance – of Rangers during the Graeme Souness and David Murray eras. There is continual misuse of language surrounding what HMRC have challenged Rangers about. The club used an employee benefit trust scheme to pay employees, including high-earning players. The key debate is whether or not it was legitimate for wages to be paid in this way or whether, in fact, the trusts should simply have been utilised for less frequent benefits in kind.

There is no question that people within Ibrox had earlier believed they would outgrow Scottish football, and made little secret of that fact. For all Rangers argued their spending power took both themselves and the Scottish game to a new level, others argued it was ruinous. Rangers' attitude, added to their success, prompted indifference and jealousy to an extent which is pertinent now. More significant, however, is the conflict between fair play within the SPL and commercial interest or necessity. Those issues are a matter for boardroom intrigue.

It seems virtually impossible that Rangers would ever cease to exist as a football force. Still, the form they would continue in if they lose the tax case can only be regarded as at least reasonably important to the cash flow of other clubs. As things stand, it is also key to the SPL's commercial deals. The league is thought to be thus far unsure as to how to deal with any Rangers slide into administration or liquidation. Which in itself is curious; rules should be in place stipulating basic penalties for such scenarios. Gretna, the last SPL team to fall into administration, were deducted 15 points. It is if Rangers were to be liquidated, and therefore have to reform and reapply to the SPL, that matters become tricky. Basically, they will be in need of broad support.

Rangers' value to the league is clear. Sky Sports have a broadcasting agreement that hinges on the screening of four Old Firm games per season, for a start. Rangers' commercial pull, not least in terms of the number of fans who follow them at home and away, is also a meaningful income stream in these troubled financial times. Those who point to the attendance of just under 18,000 for that Scottish Cup tie on Sunday as an indicator of things to come fail to recognise the Ibrox season-ticket base of more than double that figure.

For Celtic and their supporters, a quandary could therefore arise. A weak Rangers, or one that isn't even competing in the SPL, would be of a benefit to Celtic in the short term. Thereafter, there is a debate to be had about whether tens of thousands of supporters would buy season tickets for Celtic Park without the lure of meaningful Old Firm fixtures, or Old Firm fixtures at all. For Scottish football to be strong, it needs its leading clubs to flourish and those below to raise standards accordingly. A general regression, as has happened recently, shouldn't be viewed as positive just because it can increase competition.

Some of those Celtic fans argue, not unreasonably, that they would in fact relish the opportunity to prove their club could flourish regardless of Rangers' situation, thereby in a way actually dissolving the notion of an Old Firm.

When Neil Lennon, the Celtic manager, spoke last week about Rangers' "mismanagement" and how it was now "coming home to roost" he had the support of his club's board. It can only be assumed, then, that Celtic will push for severe sanctions if a tax case loss tips Rangers over the edge.

On this topic, there are so many unknowns. To think Rangers' turmoil wouldn't extend any further than Ibrox – both positively and negatively – is simplistic. The coming months may highlight precisely that.